This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to Appln. No. 99 810 596.9 filed in Europe on Jul. 6, 1999; the entire content of which is hereby incorporated by reference.
The invention is based on a switching point in a high or medium voltage switch.
A switching point of the abovementioned type is described in EP 0 147 036. A bridge switch piece fixed to an electrically conductive disk short-circuits two stationary switch pieces when the switching point is closed. A flat coil is fitted on each of the two sides of the disk in such a way that the disk can be moved between the two coils by means of electrodynamic forces, the bridge switching piece canceling or reestablishing the short circuit between the stationary switch pieces. When the switching point is closed, a current is fed into the first coil and, in the disk, effects an eddy current directed opposite to the current in the coil. The two coils have a repellent action on each other, as a result of which the movable disk is removed from the stationary coil and the bridge switch piece cancels the short circuit between the stationary switch pieces. In order to move the disk back and to bring the bridge switch piece onto the stationary switch pieces again, producing the short circuit, a current is fed into the second coil.
The invention, as is based on the object of specifying a switching point of the type mentioned at the beginning which can be opened and closed quickly and with a low expenditure on energy.
The switching point according to the invention is of axially symmetrical construction. As a result, it is possible largely to avoid undesired stray inductances, which is advantageous in particular in the case of possible commutation of the current onto a parallel path. The induction current necessary to form the forces of an electodymanic contact drive is generated in the movable bridge switch piece which carries the nominal current, as a result of which a disk-like part, which is otherwise provided to guide the induction current, and thus additional mass to be accelerated can be saved. By this means, the drive energy necessary to achieve a specific opening or closing speed of the switching point is minimized. In addition, during the opening operation, two contact gaps are produced, which are in each case bridged by one of two partial arcs connected in series. As a result of this series connection of partial arcs, the arc voltage dropping across a contact arrangement of the switching point is increased, whereby once again, in the event of a possible parallel path, commutation can be carried out particularly quickly and effectively.